EV Cure System and Low Temperature Resistance

Manufacturer: We are using EV (Efficient Vulcanization) system for high temperature resistance and low compression set. However, we note that the low temperature resistance is quite poor. Can you please explain why this is so?


John Woon (Senior Latex Consultant): What you observe is to be expected. Here is the reason why:

In "conventional" cure system where more polysulphidic x-links are formed, the x-links can undergo more reactions at elevated temperatures with new x-links being formed. If the rubber is at the same time deformed or compressed, it will show poor recovery when the force is released.

In EV system, such reactions rarely take place and hence you get both good resistance to high temperature and low compression (or tension) set.

Having said that, if there are more polysulphidic x-links, some main chain modification such as the formation of cyclic sulphide would take place. This modification would result in lower tendency of the rubber to crystallize at low temperature and hence better resistance to low temperatures.